Currently commercial office buildings do not have adequate protection against readily available chemicals and nuclear agents which terrorists can easily obtain in the open market. For example, chlorine and bromine gases can be purchased at pool supply outlets and cyanide pellets can purchased as jeweler's cleaning agents. If contaminates, such as these, are released into a building's heating, ventilation and air conditioning system [HVAC system] there may not be any perception of danger by the potential victims within the building until it is too late. In the case of cyanide, just a little bit will kill you (166 ppm—LD 50).
In the past, concerns have arisen about combustion based pollutants in the air supplied to a building's HVAC system where motor vehicles operate close to its air intakes. A protection system for such pollutants, is illustrated in U.S. Pat. No. 5,462,485 to Kinkead and designed to vary the amount of outside air drawn into a building in response to the concentration of such combustion pollutants in the outside air stream entering the building's air intake to avoid toxic levels of combustion pollutants.
Systems also have been developed to response to emergency conditions caused by the presence of smoke or similar harmful gases in buildings, see e.g., U.S. Pats. Nos. 4,380,187 and 5,720,659 to Wicks (using plumbing to provide life supporting oxygen to bathrooms within a building under pressure), 4,960,041 to Kiser (using vents and return air to exhaust interior of building), 5,215,499 to Eberhardt (using water powered fans to pressurize individual safe spaces in a building to purge contaminates in localized areas) and 6,293,861 to Berry (using pressurized air to purge a building of contaminants after they are sensed in the building. Also see German Patent issued to Kessler & Luch gmbh No. 27 43 107 (teaches cutting off inlet air to HVAC system when contaminants are detected in the inlet air stream).
The current invention recognizes that most commercial HVAC systems use return air as part of the total air circulation system. Thus, to avoid injury from toxic materials entering a building, both in the in-coming (outside) air stream and the air stream which is re-circulated (return air stream), must be monitored, as toxic materials may be released within a building and only present in the return air stream. Also the current invention adds radiological sensors, providing an addition level of protection, plus numerous enhancements, to avoid false positives.
The current invention is capable of simultaneously responding to multiple airborne contaminants found in the incoming air stream, and/or in the return air stream which re-circulated in a building, e.g., chlorine, bromine, carbon dioxide, ammonia, hydrogen cyanide, hydrogen sulfide, nitric oxide, nitrogen dioxide, among others, including radioactive agents.
Importantly the current invention introduces measures that essentially eliminate false positives from the sensors which, in their absence, might result in an expensive, unnecessary shut down of a building's HVAC system.
An object of the present invention is to provide a novel and improved system and method for responding to the presence of hazardous agents in the air streams circulating in the HVAC system of a commercial building.
Another object of the present invention is to provide a novel and improved system and method for protecting a building from airborne chemical and nuclear agents by detecting in real time their presence and immediately closing off the inlet air stream and the return air stream to the HVAC system, along with shutting off the fans, to avoid any further contamination of a building and/or injury to occupants of the building.
Still another object of the present invention is to provide a novel and improved system and method for protecting a building from airborne chemical and nuclear agents using a network of paired sensors for each agent to be sensed operable to sense parity between such sensors before activating the shut down of a building's HVAC system.
Another feature of the invention is using parity between sensors to determine if a sensor fault has occurred based on lack of parity between the paired sensors at any time the system is on line.
Another object of the present invention is to provide a novel and improved method and system for protecting a building from airborne chemical and nuclear agents wherein the building's controls activate dampers closing off inlet air stream to the HVAC system, dampers closing off the return air stream, and turn off the fans, in response to a signal from the building protection system of this invention, when a toxic agent is detected in the HVAC system's circulating air streams.
Another object of the present invention is to provide a novel and improved method and system for protecting a building from airborne chemical and nuclear agents which employs video monitors that observe and record areas of access to the building protection system and reports such video data to a remote location when unauthorized personnel attempt to access the system or the normal operation of the system is modified at the building.
A number of other objects and advantages will be apparent when reading this specification and the attached drawings.